Bart Noir, it is very unlikely that a government agency or the police would use the SW 6904. SW in general, is not the standard issued weapon for the police or the military.
It is possible that a private security company would deploy it but, SW is expensive compared to the Jericho, Tangfolio, FEG that are very popular with those enterprises. I do not think they would like to spend this kind of money.
Also a possibility is that it has been surrendered by a civilian to the police and the police turned around and sold it to a dealer.
Of course, there is no way for us here to know for sure.